Self explanatory. The Scaling option is visible, only just not editable in the animation window. This suggestion would allow the scaling variable to be edited during a frame of an animation. Preferably it would interpolate with the rest of the animation, but if not then snapping to it would still be useful.

Uses:

• For occasions in which changes to Pehkui Variables such as Hitbox Width & Height impede normal gameplay, Gestures, or Sneaking for example could be used to temporarily revert to a vanilla hitbox for purposes of playing the game.
• Animations that temporarily change scale for whatever reason that would be needed.